4.4.0 Introduction

For industrial installations the ATEX Directives [12, 15] apply, these require an hierarchical approach to explosion prevention and protection.

The ATEX Workplace Directive [15] requires the preparation of an explosion protection document that identifies the explosion hazards and specifies the prevention or protection measures to be employed.  The measures taken should be appropriate to the nature of the operation being undertaken, in order of priority and in accordance with the following basic principles:

• The prevention of the formation of explosive atmospheres, or where the nature of the activity does not allow that;                               
• The avoidance of ignition sources where an explosive atmosphere could exist; or                                               
• If ignition sources cannot be eliminated, the employment of measures to mitigate the effects of an ignition.

This approach to explosion safety, using a range of explosion prevention measures and, if the explosion risk cannot be entirely eliminated, explosion protection measures, is referred to as integrated explosion safety. Guidance on the integrated explosion safety approach can be found in EN 1127-1:2007 [31], which outlines the basic elements of risk assessment for identifying and assessing hazardous situations.  The standard also specifies general design and construction methods to help designers and manufacturers to achieve explosion safety in the design of equipment, protective systems and components. Details on a venting methodology to mitigate the effects of an explosion are given in Appendix A6.